What can a man do to be able to make milk to breastfeed?

Buy it... :-)) Well, a normal man cannot make milk to adequately feed a baby. Biologically a man does not have the type of breast tissues and appropriate hormones to make milk. Even taking hormones won't do the job! nor it is recommended. The easiest is buy the formula! or the mother can pump and the man can use that milk to feed the baby via bottle....
You can't. Although you have nipples, men don't really have ductal breast tissue, which is where the milk is produced. Good formula is a very safe and healthy food for a baby if breast feeding isn't available.